Does jdbc dataset store all rows in jvm memory

Question

I am using a java jdbc application to fetch about 500,000 records from DB. The Database being used is Oracle. I write the data into a file as soon as each row is fetched. Since

Answer 1

While increasing the fetch size may help the performance a bit I would also look into tuning the SDU size which controls the size of the packets at the sqlnet layer. Increasing the SDU size can speed up data transfers.

Of course the time it takes to fetch these 500,000 rows largely depends on how much data you're fetching. If it takes an hour I'm guessing you're fetching a lot of data and/or you're doing it from a remote client over a WAN.

To change the SDU size:

First change the default SDU size on the server to 32k (starting in 11.2.0.3 you can even use 64kB and up to 2MB starting in 12c) by changing or adding this line in sqlnet.ora on the server: DEFAULT_SDU_SIZE=32767

Then modify your JDBC URL: jdbc:oracle:thin:@(DESCRIPTION=(SDU=32767)(HOST=...)(PORT=...))(CONNECT_DATA=